If you have been following my posts on 2-stage DCFs, you may be interested in a PDF that I have written that explains where all the formulae come from. I intend to write more in the article, but it stands alone as-is, and shows how Damodaran arrives at his 2007 valuation for 3M. You can obtain the article here:
ftp://markcarter.me.uk/aswath.pdf
I was thinking of creating a javascript page that does a two-stage calculation for you, so that people don’t have to fiddle around with Excel or Fortran. All in good time, though.
Have fun.